Fuse plug



Dec. 7, 1954 G. w. VALENTINE FUSE PLUG Filed June 11, 1952 v INVENTOR. 6 r AL A 1e- A TTO/QNEYS United States Patent FUSE PLUG Gorden W. Valentine, Owosso, Mich.

Application June 11, 1952, Serial No. 292,856

7 Claims. (Cl. 200130) This invention relates to fuse plugs, and more particularly to a new and improved fuse plug of the type having a quickly removable and/or replaceable fusible element.

Many of the fuse plugs in common use today are necessarily discarded in their entirety when the fusible elemerit burns out, although the most costly parts of the plug are unaffected by the burn-out. In these plugs, the fusible element is either non-removable or its removal so difficult that only a skilled electrician or mechanic could properly effect it. This practice where an entire new plug has to be substituted obviously is expensive and undesirable.

One of the prime objects of my invention is to design. a fuse plug wherein the fusible element can be simply and quickly removed when burned out and a new element speedily substituted by any unskilled person.

Another object of the invention is to provide a fuse plug in which the fusible element is formed of a ductile, flexible material and can be easily and quickly inserted, and which is so arranged that the condition of the element can be readily observed through the transparent disc in the top of the plug.

A further object of the invention is to provide a fusible element for my fuse plug which is provided with stop means to aid in threading the element into the plug and insure its proper positioning, and to prevent either end of the fusible element, once the element burns out, from dropping out of the plug into the plug socket where an unskilled person might attempt to remove it with a metal instrument or tool and be injured.

A further object of the invention is to design a fusible element for the fuse plug which is formed from a flexible and ductile material so that the parted ends may be pulled out in their entirety without leaving any burned off portions inside the plug.

Another object of the invention is to provide a fusible element for the plug which includes a copper rivet on the one end thereof and wherein the opposite end of the element is wedged between the threaded fuse plug shell and the shell of the socket in which the plug is mounted, thus providing excellent contacts and a good connection when the plug is threaded into the socket in the fuse box.

A further object of the invention is to design a fusible element for the plug wherein the terminal contact comprises a rivet or eyelet of a more conductive material than the fusible element proper to insure that it will not burn off and drop into the socket and that no arc occurs outside the plug.

A still further object of the invention is to design a very simple and practical fusible element which can be easily and economically stamped out in large quantities.

With the above and other objects in view, the present invention consists in the combination and arrangement of parts, hereinafter more fully described, illustrated in the accompanying drawing, and more particularly pointed out in the appended claims, it being understood that changes may be made in the form, size, proportion, and minor details of construction, without departing from the spirit or sacrificing any of the advantages of the invention.

In the drawing:

Fig. l is a part sectional, side elevational view. of my improved fuse plug and fusible element, the broken lines indicating the ends of the element before they have been bent into place.

Fig. 2 is a plan view thereof.

Fig. 3 is an enlarged, perspective view of a typical fusible element.

Fig. 4 is a fragmentary, sectional view taken on the line 44 of Fig. 1.

Referring now more particularly to the accompanying drawing, a letter P generally indicates my fuse plug, which includes a body portion 10 of porcelain or other suitable insulating material, the body portion 10 being hollow as shown to form a chamber 11 and having a cap or collar 12 on the upper end thereof. A centrally disposed opening 13 is provided in the cap 12 and is covered by a mica disk 14 which is the approximate size of the upper end of the chamber, thus providing a window through which the condition of the fuse strip or element E may be observed. The outer periphery of the body portion 10 is threaded as shown and a conforming metallic shell 15 is provided thereon if desired.

A typical element E, which is broadly in the form of a thin strip or ribbon of suitable metal or alloy adapted to conduct the normal current of the circuit in which the plug is inserted, is shown in Fig. 3. This element E comprises enlarged end portions 16 and 17 connected by a neck portion 18 which burns across and parts when conducting a current which would otherwise burn out the particular circuit in which the fuse is plugged.

The portion 17 has a copper rivet or eyelet 19 riveted thereon to form the terminal contact as shown in Fig. 1 and the inner edge thereof is outwardly flared as shown at 2th and for a purpose to be presently described. A slotted, downwardly-angled passage 21 with an enlarged mid portion (not shown) for passage of the eyelet 19, is formed through the peripheral side wall of the plug P and communicates with the chamber 11. Connecting with the chamber 11 and in angular alignment with the passage 21 is another slotted passage 22, said passage being of less width than the passage 21, and this passage 22 similarly includes an enlarged central portion 23 for passage of the eyelet 19 when the element is threaded into position in the plug.

The element E is disposed in the passages 21 and 22 in the manner shown in Fig. l, and is retained in position by the flared portions 20 which cannot normally pass through the slotted passage 22. The element E has been described as typical, and it will be obvious that the proportions and dimensions of the element can be varied where it is desired to transmit greater or smaller amperages, without departing from the spirit of the invention.

The element E is inserted through the side passage 21 into the passage 22 with the portions 17 foremost, until prevented from moving further by the flared portions 20 contacting the marginal edges of the slot 22, when it will be approximately in the position indicated by the broken lines in Fig. l. The eyelet portion 19 is then bent inwardly to form the terminal contact, and a part of the portion 16 is bent tangentially along the side of the plug to form the side contact. The neck portion 18 is disposed within the chamber 11 and when an amperage overload occurs, the arcing and burning occurs at this point within the plug. The provision of the copper eyelet 19 is of particular importance in that it is more conductive than the material from which the element E is formed, and assures that no burning and arcing will occur outside the chamber at the terminal contact. The element E is preferably formed from an aluminum magnesium alloy having an electrical resistivity in the neighborhood of 17 ohms per circular mil-foot, while the copper eyelet would have an electrical resistivity of from 10.37 to 10.77 ohms per circular mil-foot.

I also Wish to direct attention to the fact that as the plug is threaded to position, the one edge of the eyelet, being disposed at an angle, makes contact first and conducts the full amperage until the plug is securely bottomed when the eyelet will be flat against the body, and to elimimate the arcing and burning at this end, I cut the metal section 17 so that the eyelet projects beyond the end of the section; this prevents arcing with the thin metal, and also represents a saving in the sheet metal.

To remove the element E once the fuse has burned out is a simple operation which can be performed by the most unskilled person. Once the plug has been removed, the

end 15 can be simply pulled out the passage'21 and the 1. A fuse plug including a chambered body member having a metallic shell on the outer periphery thereof, said body member having an angularly disposed passage having an enlarged mid section extending through the fuse plug to communicate with said chamber, said body member having also an oppositely and angularly disposed passage with a similarly enlarged mid section extending through the one end of said body member in communication with said chamber, a substantially flat, replaceable fusible conductive element having enlarged ends disposed Within said passages, and a central neck portion disposed in said chamber, the one end of said fusible element having a rivet formed of a more conductive material than said fusible element anchored thereon, said rivet passing through the enlarged mid section of said slots when said element is inserted that portion of said end being bent inwardly to form the terminal contact, the opposite end of said element being bent tangentially to lie in facial contact with said shell to form the side contact.

2. A fuse plug including a chambered body member, said body member having a passage in the sidewall of said body member in communication with the chamber, said body member having also a passage of less width than said first-mentioned passage in the end wall of the body member in communication with the chamber, a fusible element comprising enlarged end sections disposed in said passages, a neck portion connecting said end sections disposed in said chamber, the inner end of the end section in the end wall passage. being formed with laterally projecting stop means of less width than said firstmentioned passage and of greater width than said secondmentioned passage to normally limit its travel through said latter passage, and the outer end thereof having means thereon to form the terminal contact, a portion of the opposite end section of said element lying without the passage through the side wall to form the side contact.

3. A fuse plug including a chambered body member having threads on the outer periphery thereof, said body member having an angularly disposed slotted passage having an enlarged mid portion formed through the side wall of said plug in communication with the chamber, said body member having also an angularly aligned,

in the bottom wall of the plug, said passage being'of lesswidth than said first-mentioned passage, a metallic fusible element disposed in said passages, said element comprising enlarged end portions with a central reduced neck portion connecting said end portions disposed in said chamber, the inner end of the enlarged end portion in said end wall passage beingtformed with laterally projecting portions to normally limit its travel through said passage, and the outer end thereof having a rivet thereon passable through the enlarged mid portions of said passages and being bent inwardly to form the terminal contact, the opposite enlarged end portion of said fusible element partially projecting from said side wall passage and being bent to lie in facialengagement with the outer periphery of said plug to form the side contact.

4. The combination defined in claim 1 in which the rivet projects outwardlyfrom the end of said fusible element to prevent arcing at the terminal contact.

5. The combination defined in claim 3 in which said rivet comprises a split eyelet formed of a more electrically conductive material than said element which pro jects outwardly therefrom to prevent arcing at the terminal contact.

6. A fuse plug including a body member having a chamber therein, said body member having a passage in.

the side wall thereof in communication with the chamber, said body member having also a second passage of lesswidth than said first-mentioned passage in communication with said chamber, a fusible element comprising enlarged end sections disposed substantially in said passages and a neck portion connecting said end sections disposed substantially in said chamber, the inner end of the end section in said second-mentioned'passage being formed withlaterally projecting stop means of less width than said first-mentioned passage and of greater width than said second-mentioned passage to normally limit its travel through said latter passage, and the outer end thereof having means thereon to form the terminal contact, a portion of the oppositezend section of said element lying without the first-mentioned passage to'form a side con tact.

7. The combination defined in claim 6 in which said passages are. formed with enlarged mid-portions.

References Cited in the file'of this patent UNITED STATES PATENTS Number Name Date 1,308,518 Woolley .July 1, 1919 1,348,391 Clemens Aug. 3, 1920 1,524,650 Hansen Feb. 3, 1925 1,912,276 Hughson May 30, 1933 2,443,134 Garibay June 8, 1948 2,557,926 Swain et al. June 26, 1951 

